1. Related Technical Field
Related technical fields include map updating systems that update a part of, or the entirety of, map information stored in a navigation apparatus or the like to new map information, based on difference update information or total update information.
2. Related Art
Recently, many vehicles have a navigation apparatus installed therein, the navigation apparatus being operable to provide driving guidance for the vehicle and to help the driver to easily reach a desired destination. In this situation, the navigation apparatus denotes an apparatus that is operable to detect a current position of the vehicle with the use of a GPS receiver or the like, obtain map data that corresponds to the current position from a recording medium such as a DVD-ROM or an HDD or via a network, and display the obtained map data on a liquid crystal display monitor. The map data that contains the current position of the vehicle is read from the recording medium or the like, and a map image of the current position of the vehicle is rendered based on the map data and displayed on the display apparatus. Also, a vehicle position mark (i.e., the vehicle location) is superimposed on the map image. The map image is scrolled according to the movement of the vehicle, or the vehicle position mark is moved while the map image is fixed on the screen, so that, the navigation apparatus allows the driver to understand, at a glance, where the vehicle is traveling at any given moment.
New roads (newly constructed roads) are constructed every year nationwide. Also, due to the construction of the new roads, some roads no longer exist, and the formation of existing roads is changed. Thus, it is necessary to update the map data stored in the navigation apparatus at certain intervals of time. In this situation, the map data is updated by buying a new DVD and replacing an old DVD with the new one, or rewriting the contents of the HDD based on map data distributed from a map information distribution center or the like. For rewriting the contents of the HDD, there are basically two types of updating methods as described below:
One method is, when there has been a change in the roads or the like, the map information distribution center creates difference update data used for updating only the changed part. When there is some difference update data related to a specific area (e.g. an area in the neighborhood of one's home that is registered) that needs to be updated in each navigation apparatus, the map data is updated to new map data with the use of the difference update data (Japanese Patent Publication No. 2004-198841).
A second method is the map information distribution center creates total update data used for collectively updating, at regular intervals (for example, once every year), the nationwide map data to new map data that reflects the present road state, so that the map data is completely updated to the new map data by using the created total update data.